Noise reducing means for sound locator-searchlight systems



April 2, 1935.

F. R. HOUSE NOISE REDUCING MEANS FOR SOUND LOCATOR SEARCHLIGHT SYSTEMS Filed Ju ne 2B, 1934 2 Sheets-Sheet 1- INVENTOR fiqn/vk 5, H0065 T0 REMOTE GDNTROL April 1935. F. R. HOUSE 1,996,514

NOISE REDUCING MEANS FOR SOUND LOCA'IOR SEARCHLIGHT SYSTEMS Filed June 28, 1934 Zv SheetS-Sheet 2 man llllllll mm 6 )HI IJJI ll IIIFI IIJ lllllllllffl:

H16 ATTQR'NEY.

Patented Apr. 2, 1935 TED STATES Claims.

This invention relates to the problem of lo- :cating aircraft at night by means of sound, so

ithatanti aircraft searchlights and batteries may be trained upon the same. The present practice is" to employ a plurality of portable units com-- "prising a sound locator, a searchlight, and a searchlight truck, the, latter not only transportiing the searchlight and possibly hauling the. sound -l0cator as a trailer, but also supplying current l0 for operation ofthe remote control and indicator systems between the sound locator and searchlight, and for the operation of the searchlight itself. As outlined in the prior patent to M. L. Patterson, No. 1,622,392, dated March 29, 1927, the truck engine is preferably also employed for driving; theelectric generator for generating current for the above named purposes, a clutch being-employed for coupling and uncoupling the generator from the crank shaft.

The problem of locating aircraft at night, however, is becoming more and more difficult as the airplanes are being silenced by the use of reduced speed propellers, engine muffling, etc., so that it becomes very important to reduce all sounds near the sound locator to a minimum. The present invention is designed to reduce the noise from the truck engine and generator. Extreme silence is especially "desirable during the so-called tracking period. The first warning of the approach of aircraft is usually telephoned in from listening outposts several miles away. The sound locator is then manned and the power plant started in readiness for the expected attack,

at which time current is required for operating the remote control and data electric circuits, and

it is during this period that the leastlpossible' noise is desired. The searchlight is not turned on until the aircraft is approximately located, so that after the Searchlight is on, silence is not so essential, because aircraft may then be picked up by the eye, or at least the aircraft is then' closer and the noise emitted greater. Accordingto my invention, I therefore propose to provide an automatic speed control of the engine to maintain the speed very low during the tracking period,

and to only speed it up to full speed when the searchlight is turned on, requiring heavy current.

As a further means to the same end I may provide an extra mufiler which may be eutin during the tracking period and which is eliminated when the truck is on the road or, if desired, when the searchlight is in operation.

Referring to the drawings showing one form my invention may assume,

PATENT oFF cE NOISE REDUCING MEANS FOR SOUND LOCATOR-SEARCHLIGHT SYSTEMS Frank R. House, Baldwin Harbor, N. Y., assignor to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a corporation of New York Application June 28, 1934, Serial No. 732,860

.As set up on the field, the system comprises a sound. locator I, at which the listeners are located, a'searchlight 2 and algenerating truck or 'unit 3, each spaced'from the other several hundred feet. The sound locator preferably also. is provided with binoculars flto follow the target after being picked up by the sound locating horns. The position of the sealrchlight is controlled automatically or semi-automatically from the sound locator by a remote electric control system with azimuth andgelevation transmitters at the sound locator actuating azimuth and eleva-- tion motors or indicators 5 and 8 at the searchlight. The electric power for operating said system is supplied from'the truck unit 8 both before and after the searchlight is turned on. The searchlight truck is shown as provided with a generator operating handle Ill, pivoted at 2i, which serves to throw in and out the clutch H coupling the quill shaft l2 of the generator through the forward drive shaft l3 of .the truck and at the same time uncoupling said forward drive shaft from the rear portion 13' thereof. Said handle i0 may also operate to cut in an auxiliary muiiler l5 so as to lessen the noise when the engine is operating the generator 3'. The manifold pipe I6 is shown as entering the 'regular muiiler H, the muflier discharging normally through cut-out openings I8 in the exhaust pipe l9. There is shown a sleeve 20 slidably mounted on said pipe so as to close said opening it when the sleeve is moved to the right in Fig. 3,-so that an auxiliary muffler l5 connected thereto may be thrown in by this means. .For this purpose the operating lever I0 may be provided with a downwardly extending fork 22, pinned to'sleeve 20 so that when said lever I0 is moved to throw in the generator, the auxiliary mufller' I5 is automatically thrown in, and when the generator is thrown out, it is' likewise cut out.

The'engine is shown as provlde'd'with a speed governor 23 for limiting the speed of the engine. In prior constructions the governor was set so as to permit a suflicient speed at all times to produce the heavy current required for the searchlight. According to my invention, however, I provide a means for maintaining a reduced speed and consequently a low noise level when only small current is required for operating the remote "control, but provide arr automatic means for raising the speed to full power when the. am is started; The. generator is also preferably so compounded that a constant voltage is main-. tained throughout the range of engine speed. For these purposes there is shown a solenoid armature 24 differentially connected to the engine governor 23 so that'the throttle or butterfly valve 23 in e engine intake it assumes a different position under the two conditions. The valve" is represented as pivoted at 31 d is rotated by the rotation of the arm or lever 8 which is pivoted at 29 to a lever or link 30. At its lower end said link is shown as connected through a rod 3| to a core 24 of the solenoid 32. At its other end said link 30 is shown connected through a rod 33 to a bell crank lever 34, the position of which is controlled by the; governor 23. A stop screw 43 or its equivalent is for the purpose of preventing the engine speed from falling below a desired minimum, which may belittle more than v The sensitivity of the governor may be adiusted by means of bell crank lever 35, connected by spring 36 to lever 34, and the outer end of which may be adjusted to various locking positions. When only a small amount of current is passing through the solenoid 32, the core 24 will remain in the position shown in Fig. 2 by reason of the pull of the tension spring 31. when, however. the searchlight circuit is closed by closing the main switch 38, the increased current to solenoid 32 will pull the core .to the right against the stop 39, thus rotating the lever 23 clockwisejin eral results outlined, and

Fig. 2, assuming the governor to remain stationary for the moment, and thus increasing theengine speed until the governor moves lever I; to

the right sufllciently to prevent further increase.

-ent statutes, I have herein described theprincip'le-and operation of my invention,. together with the apparatus which I now consider to represent thebest embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interferin with the more gen-] e invention extends to'such use.

- Having described my invention, what I claim -.and desire to secureby Letters Patent is:

. 1. a sound locator-searchlight system for nocturnal anti-aircraft use, the combination with a sound locator, searchlight and engine driven generates, an electric remote control system between the locator and searchlight, said generator supplyin current for both said system and the searchlight, a speed governor for maintaining a slow engine speed before the searchlight is turned on to maintain a low soimd level, and automatic means responsive to the increased current required by the tfor altering the governor regulation to raise the speed to full power. 2. In a.sound locator-searchlight system for nocturnal anti-aircraft use, the combination with a sound locator, searchlight and engine driven generator, an electric remote control system between the locator and the searchlight, said generator supplying current for both said system and the searchlight, a dual speed range governor for said engine, and automatic means for shifting from-the higher to the lower range whenthe heavy searchlight current is not being drawn from said generator, to reduce engine noise. 7 3. In a sound locator-searchlight system for nocturnal anti-aircraft use, the combination with a sound locator, searchlight and searchlight generator truck, an electric remote control system between the locator and searchlight, said generator supplying current for both saidsystem and the searchlight, means for minimizing the noise of said truck engine comprising a-speed governor for maintaining a slow engine speed before the searchlight is turned on, automatic means responsive to the increased current required by the searchlight for altering the governor regulation to raise the speed to full power, an auxiliary muflier, and means for throwing said mumerin when said generator is operating.

4. In a sound locator-searchlight system for nocturnal anti-aircraft use, the combination with a sound locator, searchlight and engine driven- 8enerator, an electric remote control system between the locator and searchlight, said generator supplying current for both said system and engine, automatic means for shifting from the the searchlight, adual speed range governor for said 5 higher to the lower range when the heavy searchnocturnal anti-aircraft use, the combination with a sound locator,'searchlight and engine driven generator, an electric remote control system between the locator and searchlight, said generator supplying current for both said system. and the searchlight, a speed control for maintaining a slow engine speed before the searchlight is turned on to maintain a low sound level, and automatic.

means responsive to the increased current re'- quired bythe searchlight,:tor to 

